Traction kinking system for applying power to a trailing section of an articulated vehicle

ABSTRACT

This invention relates to an articulated machine having at least two sections with pivot points between each section, at least two sections of which are steerable. The front section is steered by a human or by a master-control system The trailing steerable section is steered by a slave controller utilizing inputs from sensors. The traction kinking system applies power to the wheels of the trailing machine section to increase or decrease the speed of the trailing section as necessary to decrease the lateral forces on the section, thereby using the traction of the wheels on the pavement to help “kink” the section behind the powered wheels with respect to the section in front of the powered wheels. By reducing these forces, the chance that the wheels will slip to the side is reduced. The system is shown as applied to a dolly and trailer pulled behind a tractor-trailer rig.

DESCRIPTION

[0001] This patent is associated with provisional patent 60/179,745.

TECHNICAL FIELD

[0002] This invention relates to a steering system for a series ofmobile, articulated, pivotally-connected machine sections, and moreparticularly to a steering system that automatically controls steerablewheels to provide automatic steering of some machine sections. Thepreferred embodiment of the invention demonstrates a way of applying theprinciples of the invention to over-the-road tractor-trailercombinations.

BACKGROUND OF THE INVENTION

[0003] Longer combination vehicles, tractor-trailer rigs with at leasttwo trailers, have always been plagued by the two problems ofinstability and lack of maneuverability. The standard Type A dolly hasachieved some degree of success over the years by striking a mid-pointbetween the two problems. It is not excessively unstable and does have alimited degree of maneuverability. However, it is not as maneuverable asdesired, and it continues to behave in an unstable manner in side windsor for sudden changes in direction.

[0004] The Type B dollies have been somewhat effective against themaneuverability problems and the instability. However, they cause otherproblems such as stresses on the rear of the forward trailer andunloading delays due to difficulty in accessing the back of the forwardtrailer.

[0005] Steerable Type A dollies address the stability problems, but areeven less maneuverable than Standard Type A dollies.

[0006] Over-the-road transport companies are finding it difficult tocompete with other freight haulers because of weight limits on the roadsand bridges. Multi-trailer arrangements are a possible solution to someof these problems because they spread the load over a longer stretch ofpavement and reduce the columnar loading on bridges. The transportationindustry is experimenting with more sophisticated types of dollies in aneffort to overcome the instabilities and the lack of maneuverabilitythat plague these multi-trailer arrangements. As the steering of thetrailing sections becomes more complex, it is often the case that thepull of the previous section is not in the direction that the wheels areintended to travel. When this is the case, it is necessary to have analternate method of applying power to the trailing section.

SUMMARY OF THE INVENTION

[0007] This invention relates to the application of power to the wheelsof the controller-steered section in such a manner as to reduce thelateral forces on the wheels, thereby reducing the amount of wheelslippage. The controller calculates the amount of acceleration orbraking to apply to the wheels by detecting the amount of sideways forceon the wheels of the controller-steered machine section. This reductionin wheel slippage aids in the creation of a reliable system for steeringseveral trailers in tandem

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a diagrammatic view of an embodiment of a gearedcornering mode dolly with traction kinking, towed behind atractor-trailer combination rig

[0009]FIG. 2 is a diagrammatic perspective plan view of geared corneringmode dolly with traction kinking

[0010]FIG. 3 is a diagrammatic view of a geared cornering mode dollywith traction kinking from top looking down

[0011]FIG. 4 is a diagrammatic back plan view of a geared cornering modedolly with traction kinking

[0012]FIG. 5 is a diagrammatic end view detail of transverse axle andaxle hanger assembly

[0013]FIG. 6 is a diagrammatic detail of location of regulator switcheson axle hanger assembly

[0014]FIG. 7 is a diagrammatic view of the kinking logic system

[0015]FIG. 8 is a diagrammatic view of air pressure converter detail

[0016]FIG. 9 is a diagrammatic view of the details of the air motorassembly

[0017]FIG. 10 is a diagrammatic view of the preferred embodiment ofinvention using a switchable geared dolly with traction kinking

[0018]FIG. 11 is a diagrammatic view of the alternative embodiment ofthe invention using hydraulic cylinders to steer dolly

[0019]FIG. 12 is a diagrammatic view of the valve box diagram of valvesused for switching between stability and cornering modes of switchablehydraulic dolly

[0020]FIG. 13 is a diagrammatic view of the valves used for switchingbetween maximum and moderate modes of switchable hydraulic dolly

[0021]FIG. 14 is a diagrammatic view of the a double-axle wagonutilizing the switchable geared type of steering and traction kinking tocontrol towing characteristics of the trailer

[0022]FIG. 15 is a diagrammatic view of the switchable “digital dolly”with traction kinking utilizing a microprocessor for steering the dolly

DETAILED DESCRIPTION

[0023]FIG. 1—Geared Cornering Mode Dolly with Traction Kinking TowedBehind a Tractor-Trailer Combination Rig

[0024]FIG. 1 illustrates a typical application of a geared corneringmode dolly 50 with traction kinking which is an alternate embodiment ofthe invention. A tractor 52 of a tractor-trailer combination has aforward trailer 54 coupled thereto via a fifth wheel 56, while a secondrear trailer 58 is coupled to the forward trailer 54 via the dolly 50 wewill be describing.

[0025]FIG. 2—Geared Cornering Mode Dolly with Traction Kinking inPerspective

[0026]FIG. 2 shows the back section of the geared cornering mode dollywith traction kinking 50 in a perspective view. Referring to thisfigure, the dolly 50 has a rigid main dolly frame 74, which in thisembodiment will be coupled to the front end of the rear trailer 58(FIG. 1) via a fifth wheel 60. The fifth wheel is mounted on an elevatedsection of a main dolly frame 74. The back part of the dolly 50 has twomain sections. The main dolly frame 74 comprises the central rigidstructural member. A transverse axle hanger assembly 75 is mounted on avertical axle hanger central pivot 126 (FIG. 4) which extends below themain dolly frame 74 and is able to swivel around on this axle hangercentral pivot 126 (FIG. 4). The details of the axle hanger assembly 75and the method of connection with a transverse axle 64 (FIG. 5) areshown in FIG. 5. The transverse axle 64 (FIG. 3) and two spaced pairs ofrunning wheels 62R and 62L, which it carries, are mounted beneath themiddle of the axle hanger assembly 75 by any conventional suspensionsystem, In this embodiment the suspension system is omitted for clarityof illustration since it is a standard assembly. The gear train, whichcontrols the steering of the transverse axle 64 (FIG. 3), is mountedabove the main dolly frame 74 and generally in front of the axle 64(FIG. 3). This gear train includes a rear partial-circular track 68,which attaches rigidly to the axle 64 (FIG. 3), a main gearbox 88, andthe several components in between. More details of the back section ofthe dolly 50 will be discussed when we examine FIG. 3 and FIG. 4.

[0027] The front of the main dolly frame 74 with the hitch latches isnot shown in this view and will be discussed later. Most of the smallerworking parts of the dolly steering system are mounted along the top ofthe main dolly frame. These will be discussed when we examine FIG. 3.

[0028]FIG. 3—View of Geared Cornering Mode Dolly with Traction Kinkingfrom Top Looking Down

[0029]FIG. 3 shows a view of the primary sections of the dolly 50 fromabove. The transverse axle 64, which was discussed above, has anattachment at the top via a track attachment assembly 66L and 66R to theextremities of a large rear partial-circular track 68. Thispartial-circular track must be somewhat longer than a semicircle toallow for rotations of more than 90 degrees. The attachment assemblies66L and 66R are designed solidly, but they attach to the back of thetransverse axle 64 so that the space directly above the axle 64 andforward and slightly backward is empty. This allows more than a full 180degrees of rotation of the axle hanger assembly 75 (FIG. 2) about avertical axle hanger central pivot 126 (FIG. 4).

[0030] The bottom of the rear partial-circular track 68 is in the sameplane with the top of the main dolly frame 74. The gear teeth on thefront of the rear partial-circular track 68 are sized to mesh with theteeth of a small gear 72 mounted on the main dolly frame 74. This rearpartial-circular track 68 passes between a roller 70 and the small gear72 on the top of the main axial member of the main dolly frame 74. Theroller 70 and the gear 72 are positioned to press tightly against thesides of the rear partial-circular track 68 so that as he gear 72rotates, it causes the rear partial-circular track 68 to move betweenthe gear 72 and the roller 70. This in turn will cause the axle 64 torotate about a vertical axis, changing the orientation of the dollyrunning wheels 62L and 62R.

[0031] The small gear 72 is rigidly attached to a large 90-degree gear76 above it, both of which rotate about the same axis. The large90-degree gear 76 is mounted high enough to easily stay clear of therear partial-circular track 68 as it moves. The large 90-degree gear 76has 45-degree teeth along its outer lower edge designed to mesh with asmaller 90-degree gear 78 rotating at a 90-degree angle to it andlocated directly below its front edge. This smaller gear 78 which isrotating around an axis parallel to the main axial member of the maindolly frame 74 is mounted on a shaft 80 which passes into a kinkinglogic system gearbox 82 through the back wall of the kinking logicsystem gearbox 82. This kinking logic system gearbox 82 keeps up withthe orientation of the rear partial-circular track 68 and of thetransverse axle 64 in order to determine when air pressure for thekinking drive system should be disabled and/or switched to braking airpressure. More details of the operation of the kinking logic system willbe discussed in FIG. 7.

[0032] A shaft 84 coming out through the front wall of the kinking logicsystem gearbox 82 goes through another wall and into the main gearbox88. The purpose of this main gearbox 88 is to change the ratio and/orthe direction of the rotational input from a front shaft 98 to a newoutput rotation of the rear shaft 84, thus determining the steeringbehavior of the dolly. A detailed discussion of this operation will bepresented in the operation section, however we will summarize thespecifications here that would be needed when ordering this gearbox froma manufacturer.

[0033] When ordering the gearbox, the following requirements will needto be specified. The input rotation enters the front of the box, and thedesired gear ratio must be available to the shaft coming out the back.Note also that the output rotation must be reversed by the gearbox.

[0034] A shaft 98 comes out the front of the main gearbox 88. The frontend of the shaft 98 connects to a 90-degree gear 92. The 90-degree gear92 connects to a larger 90-degree gear 94 in a manner that is similar tothe connections to the rear partial-circular track 68 except that gear92 is above gear 94. A smaller gear 96 below gear 94 is rigidly attachedto gear 94 so that its axis coincides with the axis of gear 94. Thissmaller gear 96 then meshes and presses tightly against the back of aforward partial-circular track 100 while a roller 102 rolls tightlyagainst the front or inside of the forward partial-circular track 100.As the forward trailer 54 (FIG. 1) turns, the forward partial-circulartrack 100 is forced to move between the roller 102 and the gear 96,causing the 90 degree gear 94, and thus the attached linkages to rotate.

[0035] The forward partial-circular track 100 is attached to the forwardtrailer 54 (FIG. 1) at its extremities via some sort of hitching devicethat allows pivoting around a vertical axis and some amount of pivotingaround horizontal axes while preventing vertical or horizontal movementat the point of hitching to provide support and pulling force. In thisembodiment, we will use standard ball hitch type latches 106L and 106Rto represent the hitch arrangements for the partial-circular track 100.The heavy central member of the dolly frame 74 attaches to a largerhitching point using a similar, but larger, hitching device that will berepresented by hitch latch 108. The forward trailer 54 (FIG. 1) must bemodified to have hitching points compatible with the dolly hitchlatches, which in this embodiment we will represent with hitch ballsmounted solidly directly to each side of a heavy central hitch ball. Theside hitch balls must be mounted slightly higher than the central ballto line up with their respective ball hitch latches 106L and 106R. Notethat the partial-circular track 100 is not solidly attached to the maindolly frame, but travels across it, in contact with it, during turns. Inthis embodiment a transverse rod 110, which is a light steel bar whichpivots around its centerpoint pivot 111 on the top of the main dollyframe 74, and which is not in any way a necessary part of the invention,is provided for convenience during hitching. It does not connect to theforward partial-circular track 100 at its ends, but allows the ends ofthe forward partial-circular track 100 to slide slightly from side toside in short slots 112L and 112R. This transverse rod 110 also providessupport for the ends of the forward partial-circular track 100 when thedolly 50 is not hitched to a towing vehicle.

[0036] At the back of the dolly, the main dolly frame 74 widens out withsupporting braces 160 to become more robust. FIG. 4 will show moredetails of the back section of the dolly.

[0037]FIG. 4—View of Geared Cornering Mode Dolly with Traction Kinkingfrom the Back Looking Forward

[0038]FIG. 4 shows a view of the back of the geared cornering mode dollywith traction kinking. Note that the transverse axle 64, which wasdiscussed above, has an attachment at the top via a track attachmentassembly 66L and 66R to the extremities of the large rearpartial-circular track 68. The attachment assemblies 66L and 66R aredesigned solidly, but they attach to the back of the transverse axle 64so that the space directly above the axle and forward is empty. Thisallows more than 180 degrees of rotation of the axle hanger assembly 75(FIG. 2) about the vertical axle hanger central pivot 126.

[0039] Below the main dolly frame 74 the heavy axle hanger central pivot126 supports and allows pivoting of the axle hanger assembly 75 and ofthe transverse axle 64 with its associated components. Thus, the axlehanger assembly 75 and the transverse axle 64 are allowed to pivot belowthe main dolly frame 74 in response to the torque applied by the rearpartial-circular track 68. More details of the axle hanger assembly 75and of its attachment to the transverse axle 64 are shown in FIG. 5.

[0040] The air motor assemblies 170 R, L that comprise the power sourcefor the kinking drive system are mounted behind the transverse axle 64on each side. Each air motor assembly 170 R, L includes gearing to slowthe rotation to the appropriate speed and to increase the torque. Theoutput from each air motor assembly 170 R, L is applied via a gear 200(FIG. 9) on a drive shaft 202 (FIG. 9) that extends out through thecenter of each wheel 62 R, L. The wheels 62 R, L and the shafts aremounted on bearings in a similar manner to the drive wheels on the backof a truck tractor. No differential is needed, because the two airmotors 170 R, L have a common air supply and will apply equal torques tothe shafts 200 they are driving. More details of these air motorassemblies 170 R, L will be shown in FIG. 9.

[0041]FIG. 5—End View Detail of Transverse Axle and Axle Hanger Assembly

[0042]FIG. 5 shows a view of a detail of the transverse axle 64 insidethe axle hanger assembly 75. Since the input to the kinking system isthe sideways force on the dolly axle 64, we must have some way ofmeasuring this force. In this alternate embodiment of the invention, thetransverse axle 64 is mounted in an axle hanger assembly 75 that allowssome movement from side to side in response to a sideways force. Thismovement is used to activate air regulator switches 190 (FIG. 6) (orsome such device) on each side, which then power the kinking system.

[0043]FIG. 5 shows a detailed view of the axle 64 mounted in the axlehanger assembly 75. The axle 64 is mounted in the center of an invertedU-shaped channel 172 in the axle hanger assembly 75. The weight on theaxle 64 is supported by a number of vertical arms 174 each of whichattach via a pivot 176 at the top to the axle 64 and via a pivot 177 atthe bottom to the lower sides of the U-shaped channel 172. When asideways force is applied to the axle 64, the vertical arms 174 swingsomewhat to the side in response to the force. At the top and bottom ofthe channel 172, roller bearings 180, 181 in partial-circular races 182,183 stabilize the axle 64 against forward and/or backward forces andagainst twisting movement.

[0044]FIG. 6—Detail of Location of Regulator Switches on Axle HangerAssembly

[0045]FIG. 6 is a detail of the location of regulator switches 183, 184on the axle hanger assembly 75. The axle 64 is shown passing through theaxle hanger assembly 75, which rotates on the vertical axle centralpivot 126. The movement of the axle 64 in response to the sidewaysforces upon it activates a regulator valve or switch 183, 184 placed oneach side of the axle 64 (FIG. 6). Full air pressure from the truck airsystem is applied to the input side of these switches 183, 184. Theswitches 183, 184 are designed to send increasing pressure to thekinking system as the sideways force increases, in just the oppositemanner to the way the force on the brake pedal reduces the pressure tothe brakes in an air brake system. During a turn, if the sidewayspressure tries to push the dolly 50 (FIG. 1) to the inside of the turn,air pressure is sent to the air motors 171 (FIG. 9) in the air motorassembly 170 L, R (FIG. 4, 9) to push the dolly wheels 62 L, R (FIG. 4)forward, relieving the pressure. If the sideways pressure tries to pushthe dolly 50 (FIG. 1) to the outside of the turn, air pressure is sentto the brake activation system to slow the dolly 50 (FIG. 1) andeliminate the risk of jackknifing. The details of how the air from eachof the regulator switches 183, 184 is routed are shown in FIG. 7.

[0046]FIG. 7—Kinking Logic System

[0047]FIG. 7 is a detail of the kinking logic system. The kinking logicsystem controls the final routing of the air pressure which does thework of kinking or un-kinking as needed. This system is located insidethe kinking logic system gearbox 82 (FIG. 3). As the rearpartial-circular track 68 (FIG. 3) and the dolly axle 64 (FIG. 3) turnfrom side to side, the shaft 80 coming into the kinking logic systemgearbox 82 (FIG. 3) from the back rotates clockwise andcounterclockwise. Inside the kinking logic system gearbox 82 (FIG. 3)another gear 186 moves in contact with a gear 185 on this shaft 80 andtransfers this rotation to a second screw shaft 188. A substantialportion of the length of this screw shaft 188 is covered with coarsesquare-edged threads. A regulator valve activator block 190 is threadedonto these threads, and the rotation of the screw shaft 188 causes thisregulator valve activator block 190 to move back and forth as the dollyaxle 64 (FIG. 3) changes orientation. The position of this regulatorvalve activator block 190 controls where the air pressure is sent fromthe regulator switches 183, 184 (FIG. 6) located on the axle 64 (FIG.3). If the regulator valve activator block 190 is to the left of itscenter position it activates a double regulator valve 191. Then the airpressure coming through the double regulator valve 191 from the leftregulator switch 183 (FIG. 6) is sent to the air motors 171 (FIG. 9) tohelp move the dolly forward and any air pressure from the rightregulator switch 184 (FIG. 6) is sent to the brake system to slow thedolly down and prevent a jackknife. If the regulator valve activatorblock 190 is to the right of its center position it activates a doubleregulator valve 193. Then the air pressure from the left regulatorswitch 183 (FIG. 6) is sent to the brake system, and any air pressurefrom the right regulator switch 184 (FIG. 6) is sent to the air motors171 to speed the dolly up. In addition, if the regulator valve activatorblock 190 is near its center position, indicating that the dolly wheels62 L, R (FIG. 3) are close to alignment with the dolly centerline, theair pressure from either of the regulator switches 183, 184 issubstantially reduced by whichever of the double regulator valves 191 or193 is activated. Since any force applied by the wheels 62 R, L (FIG. 2)parallel to the dolly centerline would simply be resisted by the hitchassembly, this reduction saves wear and tear on the system. If theregulator valve activator block 190 is substantially away from itscenter position in either direction, the air pressure from the regulatorswitches 183, 184 (FIG. 6) is not reduced.

[0048]FIG. 8—Air Pressure Converter Detail

[0049]FIG. 8 is a detail of the air pressure converter located insidethe kinking logic gearbox 82. The air pressure from the above kinkinglogic gearbox (FIG. 3) is always positive, but air brakes are activatedby a lack of pressure. The kinking logic system gearbox includes aconverter to change the positive air pressure into a lack of pressurefor the dolly and the trailer brakes. As the braking air pressure fromthe kinking logic system increases, it activates an air cylinder 192which pushes on another regulator valve 194 that is constructed like thebrake pedal on an air brake system. The air line for the trailer anddolly brakes runs through this regulator valve 194, and as the regulatorvalve 194 is pushed, air pressure is removed from the air line to thedolly and the trailer brakes, causing them to be activated.

[0050]FIG. 9—Details of the Air Motor Assembly

[0051]FIG. 9 is a detail of the air motor assembly. The two similar airmotor assemblies 170 R, L convert the air pressure sent from the kinkinglogic system into torque to drive the dolly wheels 62 L, R. (FIG. 3)Each assembly includes a system of gears to reduce the speed andincrease the torque of the air motors 171. When the air motors 171 areactivated, the shaft 204 and gear 206 carrying the output rotation fromthe air motor assembly 170 engages a gear 200 on the end of the axleshaft 202 that extends out through the center of the wheels 62 L, R(FIG. 3) on each side of the dolly. This shaft 202 then causes thewheels 62 R, L to drive forward in a manner similar to the way the drivewheels of the truck tractor operate. Since the two air motor assemblies170 R, L share a common air pressure source, no differential gears areneeded to equalize the torques on the wheels.

[0052]FIG. 10—Preferred Embodiment of Invention Using a SwitchableGeared Dolly with Traction Kinking

[0053]FIG. 10 shows a view from above of a preferred embodiment of theinvention, using a switchable geared dolly with traction kinking. Thispreferred embodiment of the invention is very similar to the gearedcornering steerable embodiment of the invention except that the dollylength is adjustable and the steering gear ratio can be changed withoutstopping the vehicle. This allows the dolly to be operated as aStability Steerable dolly at higher speeds on the open road, thenshifted into a different mode to operate as a Cornering Steerable dollyfor better cornering ability at lower speeds.

[0054]FIG. 10 shows a view of the primary sections of the dolly 50 fromabove. The transverse axle 64 has an attachment at the top via a trackattachment assembly 66L and 66R to the extremities of a large rearpartial-circular track 68. The attachment assemblies 66L and 66R aredesigned solidly, but they attach to the back of the transverse axle 64so that the space directly above the axle and forward and somewhatbackward is empty. This allows more than a full 180 degrees of rotationof the axle hanger assembly about a vertical axle hanger central pivot126 (FIG. 4), located directly under the fifth wheel 60. The bottom ofthe rear partial-circular track 68 is in the same plane with the top ofthe main dolly frame 74. The gear teeth on the front of the rearpartial-circular track 68 are sized to mesh with the teeth of a smallgear 72 mounted on the main dolly frame 74 a. This rear partial-circulartrack 68 passes between a roller 70 and the small gear 72 on the top ofthe main axial member of the trailer frame 74. The roller 70 and thegear 72 are positioned to press tightly against the sides of the rearpartial-circular track 68 so that as the gear 72 rotates, it causes therear partial-circular track 68 to move between the gear 72 and theroller 70. This in turn will cause the axle 64 to rotate about avertical axis, changing the orientation of the dolly running wheels 62Land 62R. The small gear 72 is rigidly attached to a large gear 76 aboveit, both of which rotate about the same axis. The large gear 76 ismounted high enough to easily stay clear of the rear partial-circulartrack 68 as it moves. The large gear 76 has 45 degree teeth along itsouter lower edge designed to mesh with a smaller gear 78 rotating at a90 degree angle to it and located directly below its front edge. Thissmaller gear 78 which is rotating around an axis parallel to the mainaxial member of the main dolly frame 74 is mounted on a shaft 80 whichpasses into a kinking logic system gearbox 82 through the back wall ofthe kinking logic system gearbox 82. This kinking logic system gearbox82 keeps up with the orientation of the rear partial-circular track 68and of the transverse axle 64 in order to determine when air pressurefor the kinking drive system should be disabled and/or switched tobraking air pressure.

[0055] A shaft 84 coming out through the front wall of the kinking logicsystem gearbox 82 goes through another wall and into a neutral lockgearbox 86 through the back wall of the neutral lock gearbox 86. Thisneutral lock gearbox 86 performs its functions at the beginning and atthe end of each shifting sequence. It starts each mode shifting sequenceby disconnecting all steering gears in front of the neutral lock gearbox86 from all steering gears behind it and then locking the gears behindit into a static position. Then after all other shifting operations arecompleted, and when a forward enabling switch 132 indicates that theforward section is aligned, the neutral lock gearbox 86 completes thesequence by unlocking and reconnecting the gears behind it to the gearsin front of it. Since no shifting sequence can begin unless a rearenabling switch 150 has indicated that the rear section is in alignment,this method assures that at the completion of each shifting sequence,all sections are properly aligned and centered. The operation of thisrear-enabling switch 150 will be dealt with more fully later on in thissection In practice, of course, all these events may take place in avery short interval of time, since all the actions are automaticallycontrolled by air pressure. It is worth noting here that while theneutral lock gearbox 86 has the back section locked, the dolly 50 willbe operating in the standard non-steerable A mode. This mode could thusbe easily made available if desired, but it would not have an advantageover the other two modes, which are available.

[0056] A shaft 87 coming out through the front wall of the neutral lockgearbox 86 goes through another wall and into the main gearbox 88. Thepurpose of this main gearbox 88 is to select the dolly operating mode bychanging the ratio and/or the direction of the rotational input from afront shaft 90 to a new output rotation of the rear shaft 87. A detaileddiscussion of this operation will be presented in the operation section,however we will summarize the specifications here which would be neededwhen ordering this gearbox 88 from a manufacturer.

[0057] When ordering the gearbox 88, the following requirements willneed to be specified. All gear shifting will be performed byhigh-pressure air. All gear positions must be stable; i.e. no changes ingear position can occur if no high-pressure air is applied to thesystem. The input rotation enters the front of the box, and two gearratios must be available to the shaft coming out the back. The gearshifting will be performed by only two high-pressure air lines. Pressureon the first air line, which we will call the Stability air line 154,must cause the output rotation to be shifted to straight or forward,with the magnitude of the gear ratio being equal to the value calculatedin the theory section for Stability mode. This gear ratio will depend onthe relative lengths of the dolly 50 and the rear trailer 58 (FIG. 1),but will in general be around 0.75. Pressure on the second airline,which we will call the Cornering air line 156, will cause the outputrotation to be shifted to reversed with a gear ratio of −1 (−1 rotationout to the back/one rotation in from the front). In addition to thegearing requirements, the main gearbox 88 will provide some control andinformation functions. The main gearbox 88 must activate switches whenin a particular mode which will show the main gearbox 88 status to thedriver using indicator lights 153 on a control box 152 in the driverscab. A valve must also be provided inside the main gearbox 88 that willcut off air pressure to the traction kinking system when the gearbox 88is not in the cornering mode. When the main gearbox 88 is shifted backinto cornering mode, the air pressure will be once again supplied to thetraction kinking system for assistance in turning corners.

[0058] When the rear enabling switch 150 detects alignment, the airpressure is passed through the enabling switch 150 on to the neutrallock gearbox 86 and the mode switching operation is initiated. When theforward enabling switch 132 detects alignment, the air pressure ispassed on to the main gearbox 88 to allow completion of the modeswitching operation At this point the air is passed on back to theneutral lock gearbox 86, to allow the reconnection of the back sectionof the gear train.

[0059] The control box 152 will be located in the driver's cab. The faceof the control box 152 will have two indicator lights 153, one for eachmode. The control box 152 will have an air valve that will turn on highpressure air to either the stability air line 154 or the cornering airline 156, but not to both, with the other line in each case dumped toatmosphere. Two high-pressure air lines will be routed between thecontrol box and the dolly. A front shaft 90 coming out the front of themain gearbox 88 is the outer section of a splined shaft 90 havingsplines on the inside. The inner section of a forward shaft 98 havingsplines on the outside, slides inside the outer splined front shaft 90.These splined shafts 90, 98 are designed to allow the length of the maindolly frame 74 to be adjusted as needed for different rear trailer 58lengths. Similarly, at a joint 144, a smaller main dolly frame 74 bsection slides into a larger main dolly frame 74 a section, allowing themain frame to be easily adjusted. Two pin and lock sets 146 and 148secure this attachment to prevent slippage or movement during operation.The front end of the splined shaft 98 connects to a 90 degree gear 92.The 90 degree gear 92 connects to a larger 90 degree gear 94 in a mannerthat is similar to the connections to the rear partial-circular track 68except that gear 92 is above gear 94. A smaller gear 96 below gear 94 isrigidly attached to gear 94 so that its axis coincides with the axis ofgear 94. This smaller gear 96 then meshes and presses tightly againstthe back of a forward partial-circular track 100 while a roller 102rolls tightly against the front or inside of the track. As the forwardtrailer 54 (FIG. 1) turns, the forward partial-circular track 100 isforced to move between the roller 102 and the gear 96, causing the 90degree gear 94, and thus the attached linkages to rotate. A roller 104is mounted on the forward partial-circular track 100 with mountingbraces 105. The roller 104 is not attached to the main dolly frame 74,but rotates with the forward partial-circular track 100. The rollermounting brace 105 passes above the roller 102 and below gear 94 as theforward partial-circular track 100 moves. When the forward section iscentered, the roller 104 will be in a position which presses a forwardenabling switch 132, enabling the completion of a shifting sequence. Theforward partial-circular track 100 is attached to the forward trailer 54(FIG. 1) at its extremities via some sort of hitching device that allowspivoting around a vertical axis and some amount of pivoting aroundhorizontal axes while preventing vertical or horizontal movement at thepoint of hitching to provide support and pulling force. In thisembodiment, we will use standard ball hitch type latches 106L and 106Rto represent the hitch arrangements for the partial-circular track 100.The heavy central member of the dolly frame 74 attaches to a largerhitching point using a similar, but larger, hitching device that will berepresented by hitch latch 108. The forward trailer 54 (FIG. 1) must bemodified to have hitching points compatible with the dolly hitchlatches, which in this embodiment we will represent with hitch ballsmounted solidly directly to each side of a heavy central hitch ball. Theside hitch balls must be mounted slightly higher than the central ballto line up with their respective ball hitch latches 106L and 106R. Notethat the partial-circular track 100 is not solidly attached to the maindolly frame 74 a,b, but travels across it, in contact with it, duringturns. In this embodiment a transverse rod 110, which is a light steelbar which pivots around its centerpoint pivot 111 on the top of the maindolly frame 74, and which is not in any way a necessary part of theinvention, is provided for convenience during hitching. It does notconnect to the forward partial-circular track 100 at its ends, butallows the ends of the forward partial-circular track 100 to slideslightly from side to side in short slots 112L and 112R. This transverserod 110 also provides support for the ends of the forwardpartial-circular track 100 when the dolly 50 is not hitched to a towingvehicle.

[0060] Moving toward the back of the dolly, a roller 114 is mounted in amanner similar to the front roller 104 so that its mounting brace 115passes between gear 72 and the roller 70 as the gear 72 causes the rearcircular track 68 to move. When the axle 64 is perpendicular to the maindolly frame 74, the roller 114 causes the rear enabling switch 150 to beactivated, enabling the initiation of a mode shifting sequence when thedriver has signaled for a mode change. The main dolly frame 74 widensout with supporting braces 160 in the back to become more robust. FIG. 4will show more details of the back section of the dolly.

[0061]FIG. 11—Alternative Embodiment of the Invention Using HydraulicCylinders to Steer Dolly

[0062]FIG. 11 shows an alternative embodiment of the invention involvinghydraulic cylinders. In this embodiment, which we will call theswitchable hydraulic dolly with traction kinking, the input to thesteering system is via hydraulic cylinders A 348 and B 350 located nearthe front of the dolly 50. The hoses 301L and 301R from these cylindersA 348 and B 350 go directly to a valve box 300 that can be locatedanywhere that is convenient and which will control the mode switchingThe output hoses from the valve box 300 go to the four hydrauliccylinders C 352, C′ 354, D 356, and D′ 358 mounted toward the back ofthe dolly 50. The cylinder C′ 354 is mounted directly below cylinder C352 and has common pivot points 334 and 336 with cylinder C 352. Thecylinder D′ 358 is mounted directly below cylinder D 356 and has commonpivot points 338 and 340 with cylinder D 356. These extra cylinders willbe used to provide two extra modes for the switchable hydraulic dolly,the moderate stability mode and the moderate cornering ability mode. Themoderate stability mode will produce less stability than the maximumstability mode, but will have slightly more cornering ability. Themoderate cornering ability mode will have less cornering ability thanthe cornering ability mode, but will be slightly more stable. Note thatany number of modes can be provided by simply adding valves andcylinders.

[0063] All six of the cylinders for the switchable Hydraulic dolly areidentical. All six cylinders have their bases mounted on reinforcedmounting beams 344 and 346 welded above the main dolly frame 74. Themounting beams 344 and 346 are positioned so that each cylinder can bemounted having its axis parallel to the centerline of the dolly 50 whenthe vehicles are traveling in a straight line. This configurationminimizes non-linearities when the vehicle is traveling at speed alongfairly straight roads. The rear pivot points 336 and 340 of cylinders C352, C′ 354, D 356, and D′ 358 attach to a robust member, which isequivalent to the track assembly 66L 66R of the Geared CorneringSteerable embodiment (FIG. 3), rising from the transverse axle 64 insuch a way as to allow free pivoting. (This member is beneath rear pivotpoints 336 and 340, and above the axles 64, so is not shown in thisview.) Each cylinder is attached so that its axis is horizontal.

[0064] The structural portion of the back of the switchable hydraulicdolly with traction kinking is very similar to the back of the gearedcornering mode dolly with traction kinking discussed above. Please referto FIGS. 4, 5, 6, 7 and 8 for more details on this section. The tractionkinking system is identical to that of the switchable geared dolly withtraction kinking except that the screw shaft in the kinking logicgearbox is turned by a hydraulic motor acting as a measurement device inthe hydraulic line from cylinder A.

[0065] We will now move back to FIG. 11. Attached above the point oneach side of the dolly where the hydraulic cylinders C 352, C′ 354, D356, and D′ 358 attach to their axle pivot point 336 and 340, is a solidframe 360 which extends forward in such a manner as to clear the maindolly frame 380 as it rotates. At the point where this solid frame 360crosses the center of the main dolly frame 380, a projection 362 extendsforward with a roller 364 at the end. When the transverse axle 64 (FIG.3) is aligned for straight forward movement, this roller 364 depressed aswitch 366, which will enable the initiation of a mode switchingoperation by the valve box. In a similar manner, a solid frame 368extends backward from its attachment at the forward pivot points 370Land 370R of cylinders A 348 and B 350. When the forward section isaligned for straight forward motion, a roller 372 will activate aforward switch 374 to allow completion of a mode switching operation.

[0066] The hitch latches 376L,R, 378 for the switchable hydraulic dollyare essentially identical to those of the geared cornering mode dollywith traction kinking embodiment of the invention. The valve box 300 formode switching can be located anywhere on the frame that is convenientwith hoses running to each cylinder. The details of its operation willbe dealt with in the operation section.

[0067]FIG. 12—Valve Box Diagram of Valves Used for Switching betweenStability and Cornering Modes of Switchable Hydraulic Dolly

[0068]FIG. 12 shows a symbolic representation of the valves used forswitching between the stability and the cornering modes with theswitchable hydraulic dolly. These valves are located inside the valvebox, and the switching is performed by air operated cylinders. Valve 302connects cylinder A 348 (FIG. 11) to cylinder C 352 (FIG. 11) whenswitched down. Valve 304 connects cylinder B 350 (FIG. 11) to cylinder D356 (FIG. 11) when switched down. Valve 306 connects cylinder A 348(FIG. 11) to cylinder D 356 (FIG. 11) when switched up. Valve 308connects cylinder B 350 (FIG. 11) to cylinder C 352 (FIG. 11) whenswitched up. Air cylinders 310 and 312 switch the ganged valves downwhen activated, and air cylinders 314 and 316 switch the ganged valvesup when activated.

[0069] As will be discussed in the section on operation, cylinder A 348(FIG. 11) will be connected to cylinder C 352 (FIG. 11) when thestability modes are being used and cylinder B 350 (FIG. 11) will beconnected to cylinder D 356 (FIG. 11). This is the position that isshown in FIG. 7. When the air cylinder below the valves in the diagramis actuated, the ganged valves will switch to the up position, whichwill correspond to the cornering modes. In these modes, cylinder A 348(FIG. 11) will be connected to cylinder D 356 (FIG. 11) and cylinder B350 (FIG. 11) will be connected to cylinder C 352 (FIG. 11).

[0070]FIG. 13—Diagram of Valves Used for Switching between Maximum andModerate Modes of Switchable Hydraulic Dolly

[0071]FIG. 13 shows a symbolic representation of the valves used forswitching between the maximum and the moderate modes with the switchablehydraulic dolly. These valves are located inside the valve box, and theswitching is performed by air operated cylinders. Valve 328 connectscylinder C 352 (FIG. 11) to cylinder C′ 354 (FIG. 11) when switcheddown. Valve 330 connects cylinder C′ 354 (FIG. 11) to cylinder D′ 358(FIG. 11) when switched up. Valve 332 connects cylinder D 356 (FIG. 11)to cylinder D′ 358 (FIG. 11) when switched down. Air cylinders 320 and322 switch the ganged valves down when activated, and air cylinders 324and 326 switch the ganged valves up when activated.

[0072] As was discussed above, a cylinder C′ 354 (FIG. 11) which isidentical to cylinder C 352 (FIG. 11) is located directly below cylinderC 352 (FIG. 11) and is attached to the same pivot points as cylinder C352 (FIG. 11). Similarly, a cylinder D′ 358 (FIG. 11) which is identicalto cylinder D 356 (FIG. 11) is located directly below cylinder D 356(FIG. 11) and is attached to the same pivot points as cylinder D 356(FIG. 11). In the moderate modes, the hydraulic fluid from the frontinput cylinders is shared between cylinders C 352 (FIG. 11) and C′ 354(FIG. 11) and between cylinders D 356 (FIG. 11) and D′ 358 (FIG. 11). Asa result, the movement of the dolly axle will be only half as much as ifthe fluid had not been shared. In the maximum modes, the fluid sharingis disabled, and the two cylinders C′ 354 (FIG. 11) and D′ 358 (FIG. 11)simply'share a common reservoir of fluid as their pivot points move. Theposition that is shown in FIG. 13 (FIG. 11) is the moderate positionwith the input fluid being shared between cylinders C 352 (FIG. 11) andC′ 354 (FIG. 11) and between cylinders D 356 (FIG. 1) and D′ 358 (FIG.11). If air is applied to the bottom air cylinders, the ganged valveswill switch to their up positions, and the sharing will be disabled forthe maximum mode. Cylinder C′ 354 (FIG. 11) is now connected to cylinderD′ 358 (FIG. 11) for fluid sharing. Since they attach on opposite sidesof a pivot point, any gain by one should correspond to a loss by theother.

[0073]FIG. 14—a Double-Axle Wagon Utilizing the Switchable Geared Typeof Steering and Traction Kinking to Control Towing Characteristics ofthe Trailer

[0074]FIG. 14 shows a double-axle trailer or wagon 550 that utilizesswitchable geared steering with traction kinking. This wagon 550 isdesigned to be pulled behind a three-quarter ton pickup, so it will beaccordingly sized down somewhat from the switchable geared dolly withtraction kinking 50 (FIG. 1). As was true for the switchable geareddolly with traction kinking (FIG. 1), however, this wagon 550 willrequire three hitch balls on the towing vehicle. The steering system forthis wagon 550 is identical to that for the switchable geared dolly withtraction kinking 50 (FIG. 1) except that control and shifting by thedriver will utilize 12 volt solenoids and/or 12 volt DC motors insteadof the air cylinders used by the switchable geared dolly with tractionkinking 50 (FIG. 1). The gearbox 88 will be accordingly selected ormodified to be compatible with the above. Gear ratios may also besomewhat different for the wagon 550 than for the dolly. The backportion of the trailer or wagon 504 will be permanently attached to theraised section of the front part of the main wagon frame 552, so therewill be no need for the fifth wheel that was present on the dolly.

[0075] The traction kinking system must also be modified to operate on12 volt DC power, and an extra battery may be needed to supply theadditional current The air motors powering the steering wheels will bereplaced by 12 volt DC motors similar to the engine starting motorscommonly found on passenger vehicles. The regulator switches and valveswill be replaced by variable resistance rheostats. Again, the tractionkinking system will be disabled when the steering wheels of the wagonare aligned with the centerline of the wagon tongue.

[0076]FIG. 15—Switchable “Digital Dolly” with Traction Kinking Utilizinga Microprocessor for Steering the Dolly

[0077] The switchable digital dolly with traction kinking 50 shown inFIG. 15 is identical to the original switchable geared dolly withtraction kinking except that the steering information is transferredfrom the front to the back of the dolly 50 by microprocessors 850 and852. The software in microprocessors 850 and 852 will do all modeswitching so that no gearbox will be required. Full redundancy is shownhere for all the electronic components to minimize the consequences offailures, although this is optional to the invention.

[0078] At the front of the dolly 50, two identical optical pulserotation encoders 854 and 856 will record the rotation of the forwardgear 874 and transfer this information via pulse counting circuits 858and 860 to the two identical microprocessors 850 and 852. At the rear ofthe dolly 50 two other identical optical pulse rotation encoders 862 and864 will record the rotation of the rear gear 876 Two reversible airmotors 866 and 868 geared down to a moderate speed will provide theenergy for turning the axle 64 when the software detects that movementis required. These air motors 866 and 868 are provided with automaticbraking mechanisms which lock the gear train into position at times whenno action is required of the air motors 866 and 868. Loss of airpressure will also activate the braking mechanisms.

[0079] The software in the microprocessors 850 and 852 will compare thenumber of rotations input from the front to the number of rotationsinput from the back. For a 1-to-1 reverse ratio, the software willcontrol the air motors 866 and 868 to force exactly the same number ofreverse rotations from the back as it received forward rotations fromthe front. A positive rotation in from the front is one that resultswhen the forward trailer turns more to the right with respect to thedolly centerline. Other gear ratios for other modes would be handled bysimple mathematical manipulation of the pulse counts from the backencoders. The primary microprocessor 850 would be in control at any timewith the secondary microprocessor 852 continually performing a check onthe operation of the primary microprocessor 850. Any significantdiscrepancies would be reported to the driver as a warning and thedriver would have the ability to switch to the secondary system if thesituation warranted it.

[0080] The alignment of the transverse axle hanger assembly is alsomonitored by the computer utilizing the input from the optical rotationencoders. Thus, the kinking logic system is also replaced in this modelby software in the computer. During a turn to the left, air pressurefrom the left regulator switch on the dolly axle is routed to the airmotors and air pressure from the right regulator switch is routed to thekinking braking system. During a turn to the right, air pressure fromthe left regulator switch on the dolly axle is routed to the kinkingbraking system and air pressure from the air pressure from the rightregulator switch is routed to the air motors. Additionally, when thedolly wheels are more in alignment with the dolly centerline, the airpressure from either regulator switch is substantially reduced to savewear-and-tear on the kinking system.

[0081] The traction kinking input system and the traction kinking outputor power system for the switchable digital dolly would be identical tothose for the switchable geared dolly with traction kinking. Pleaserefer to FIGS. 4, 5, 6, 7, and 8. Traction kinking would be disabled inany stability type mode.

[0082] Operations

[0083] An Alternative Embodiment of the Invention—a Dolly That Operatesin the Cornering Steerable Mode by Using Gears, and That Uses TractionKinking to Assist in Turning Corners

[0084] Introduction

[0085] As discussed in the details Section, an alternative embodiment ofthe invention is the geared cornering mode dolly with traction kinking.The primary feature of interest in this alternative embodiment of theinvention is its use of the traction kinking to assist in turningcorners. The steering ratio (turns out the back/turns in at the front)for this embodiment is negative and the absolute value of the ratio isgreater than 1.0. This ratio produces a steering behavior that is veryresponsive, and the dolly makes very aggressive steering moves in orderto stay pretty much directly behind the forward trailer. This behaviorproduces good cornering capabilities for the described tractor-trailercombination. However, this behavior also produces substantial sidewaysstresses on the dolly axle. In fact, the dolly may actually slidesideways in sharp turns if no precautions are taken. The purpose of thetraction kinking system is to prevent this sideways force by eitherbraking or by driving the dolly wheels forward at the appropriate times.

[0086] During a turn, the pull of the forward trailer on the front ofthe geared cornering mode dolly with traction kinking tends to stretchout the dolly or to “un-kink” it. In order to prevent the dolly fromcutting directly across the corner, we must have some force that resiststhis stretching force. We will call any force a “kinking force” if itresists this stretching force. Most current dolly models use theresistance of the dolly tires to sideways motion as the primary kinkingforce. The exception to this rule is the Type B dolly, which exerts atorque on the back end of the forward trailer in order to kink the backtrailer. The geared cornering mode dolly with traction kinking that isan alternative embodiment of the invention, is the first dolly thatutilizes traction kinking instead of, or in addition to, the two typesof kinking forces described above. The traction kinking input systemsenses when kinking is needed. Power is then applied to the dolly wheelsvia air motors in the traction kinking drive system to provide theneeded kinking force.

[0087] Before we examine the traction kinking system in detail, we willcover the general features of this geared cornering mode dolly withtraction kinking.

[0088] Input to the Steering System

[0089] In overview, the input to the steering system of the gearedcornering mode dolly with traction kinking is derived from the anglebetween the forward trailer 54 and the dolly 50. This input will bepicked up by the forward partial-circular track 100 and transferred viathe forward part of the geartrain into the main gearbox 88. The maingearbox 88 changes the direction of the rotation and also increases thevalue of the gear ratio so that slightly more rotations come out of theback than go into the front. This ratio will determine thecharacteristics of the dolly's steering. Then the output from thegearbox 88 is transferred via the kinking logic system gearbox 82 andthe back part of the geartrain to the rear partial-circular track 68.The back of the rear partial-circular track 68 is attached to the axle64 of the dolly, and causes the axle 64 to rotate about its centralpivot point 126 in response to the original input from the front of thedolly. As we mentioned above, the angle between the forward trailer 54and the dolly 50 provides the input for our steering system. As thisangle varies during a turning operation, we see from FIG. 3 that theforward partial-circular track 100 moves between the roller 102 and thesmall gear 96. These two rotary members are pressed tightly against thetwo sides of the forward partial-circular track 100 to prevent slippageof the gear 96, so that the gear 96 is forced to rotate by the movementof the forward partial-circular track 100. This rotational movement isratioed up by 90 degree gear 94 and converted to rotation about an axisparallel to the main axial member of the main dolly frame 74 by the 90degree gear 92. The shaft 98 then carries this rotational movement intothe main gearbox 88 mounted on the main dolly frame 74.

[0090] Operation of the Gearbox

[0091] The main gearbox 88 reverses the direction of the rotation whichis input from the front and also ratios the rotation up so that moreturns come out of the back than went into the front of the main gearbox88.

[0092] The specifications for ordering the main gearbox 88 were given inthe description section, so we will only review them here. The inputrotation enters the front of the box, and the desired gear ratio must beavailable to the shaft coming out the back. Note also that the directionof the output rotation must be reversed by the gearbox.

[0093] Operation of the Kinking Logic System Gearbox

[0094] The shaft 84 coming out through the back wall of the main gearbox88 goes through another wall and into the kinking logic system gearbox82. The kinking logic system determines the direction and/or the amountof torque needed for proper kinking of the dolly and the back trailer.If the tractor-trailer combination rig is making a left turn, a pull tothe left on the axle will indicate that the drive wheels of the dollyshould be speeded up, so air pressure will be applied to the air motorsto cause the dolly to move forward faster. If the axle experiences apull to the right during a left turn, it indicates that the trailer ismoving too fast, trying to push the dolly along. In this case, thebrakes will be applied on both the dolly and on the trailer it issupporting to slow the trailer back down and prevent the dolly wheelsfrom being pushed sideways. In a similar fashion, a pull to the leftduring a right turn will cause the brakes to be applied, while a pull tothe right during a right turn will cause air to be applied to the airmotors powering the wheels.

[0095] In an air motor, an increase in air pressure causes an increasein torque. The automatic braking system is also designed so that anincrease in pressure causes more braking to be applied. The amount oftorque or braking can then be regulated by regulating the air pressuresupplied to these systems. The regulation of the air pressure isperformed by two complementary valving systems. The regulator switchesat the ends of the axle hanger assembly take in air from the main airsupply and output pressures that are related to the amount of sidewayspull experienced by the axle. These pressures are then sent to thekinking logic system, where they are further reduced if necessary, andthen sent to either the braking system or the air motors as appropriate.The screw switch in the logic system detects the angle between the dollyaxle and the centerline of the dolly. If the angle is close to 90degrees, then the dolly wheels will be nearly in line with the dolly andapplication of traction, either forward or backward, will beineffective. In this situation, the air pressure is further reduced bythe regulator switches in the kinking logic system to reduce wear andtear on the system. If the angle between the dolly axle and the dollycenterline is significantly different from 90 degrees, then the wheelsare not aligned with the dolly and traction will be quite effective inproducing kinking of the dolly. Accordingly, the regulator switches inthe kinking logic system do not reduce the pressures received from theaxle regulator switches, but simply route them to the braking system ifthe trailer needs slowing or to the air motors if the trailer needsspeeding up.

[0096] Output from the Gearbox to Steer the Dolly Axle

[0097] In FIG. 3 the shaft 80 carries the output rotational movementfrom the kinking logic system gearbox 82 to the gear 78. The gear 76then picks up this movement, ratios it back down, and converts it backto rotation about a vertical axis. Gear 72, with the help of roller 70then converts this rotational movement into movement of the rearpartial-circular track 68 which then causes the transverse axle 64 torotate about its central pivot point, steering the dolly 50.

[0098] The Traction Kinking Input System

[0099] The traction kinking input system is shown in FIGS. 5 and 6. InFIG. 5 we see that the input to this system comes from the sidewaysforce on the axle of the dolly with traction kinking. The axle ismounted so that it can freely move a limited distance in response tosideways pulls. When the dolly orientation becomes such that the pull ofthe forward trailer places a sideways pull on the dolly, the movement ofthe axle is sensed by the regulator switches on either side of the axlehanger assembly. These regulator switches apply high-pressure air toeither operate the brake system or to power the air motors that move thewheels forward.

[0100] The Kinking Output or “Power” System

[0101] The automatic braking system, which is a part of the gearedcornering mode dolly with traction kinking, functions to resist kinkingwhen it is inappropriate. In this capacity it acts as an effectivejackknife prevention device. A jackknife is caused when the back trailerattempts to roll forward during a turn causing the dolly to “kink” intoa jackknife configuration. The automatic braking system detects theexcessive sideways push on the dolly axle toward the outside of a turnthat is characteristic of a jackknife situation and intercedesimmediately by applying the brakes to the trailer and to the dolly. Notethat the positive pressure supplied by the kinking logic system must betransformed into a lack of pressure in order to apply the air brakes.

[0102] The other half of the kinking output system is the air motorsthat push the dolly wheels forward to provide more kinking force when itis needed. A pull on the dolly axle toward the inside of a turnindicates that more kinking force is needed. The same air pressure issupplied to both of the air motors, assuring that the torques on the twosides are equal. The pressure of the air is related to the amount ofsideways pull that is being experienced by the axle.

[0103] Summary and Miscellaneous for Geared Cornering Mode Dolly withTraction Kinking

[0104] In summary, the input to the steering system of the dolly 50 isthe angle between the back of the forward trailer 54 and the dolly 50.The output from the system is the orientation of the transverse axle 64,and thus of the running wheels 62R and 62L of the dolly 50. Themanipulation of the input by the gearbox 88 is the key to the steeringcharacteristics of the dolly 50 in this alternative embodiment of theinvention.

[0105] A Dolly Using Gears and a Gearbox for Switching between SteeringModes, and Traction Kinking for Assistance in Turning Corners

[0106] Introduction

[0107] The primary features of interest in this preferred embodiment ofthe invention is its switchability between at least two steering modeswithout stopping the vehicle and its use of traction kinking for turningcorners. At least one of these steering modes must be designed toprovide stability at higher speeds, and at least one mode must bedesigned for better cornering ability and maneuverability. In thispreferred embodiment the stability mode is the mode designed to providestability at higher speeds. In this preferred embodiment, the corneringability mode is the mode designed to provide more maneuverability. Thismode corresponds to a type of steering that would be produced by crossedsteering arms.

[0108] Input to the Steering System

[0109] In overview, the input to the steering system of the switchablegeared dolly with traction kinking is derived from the angle between theforward trailer 54 and the dolly 50. This input will be picked up by theforward partial-circular track 100 and transferred via the forward partof the geartrain into the gearbox 88. The gearbox 88 chooses the mode,which will determine the characteristics of the dolly's steering. Thenthe output from the gearbox 88 is transferred via the back part of thegeartrain to the rear partial-circular track 68. The back of the rearpartial-circular track 68 is attached to the axle 64 of the dolly, andcauses the axle 64 to rotate about its central pivot point 126 inresponse to the original input from the front of the dolly.

[0110] As we mentioned above, the angle between the forward trailer 54and the dolly 50 provides the input for our steering system. As thisangle varies during a turning operation, we see from FIG. 3 that theforward partial-circular track 100 moves between the roller 102 and thesmall gear 96. These two rotary members are pressed tightly against thetwo sides of the forward partial-circular track 100 to prevent slippageof the gear 96, so that the gear 96 is forced to rotate by the movementof the forward partial-circular track 100. This rotational movement isratioed up by 90 degree gear 94 and converted to rotation about an axisparallel to the main axial member of the main dolly frame 74 by the 90degree gear 92. The splined shafts 98 and 90 then carry this rotationalmovement into the main gearbox 88 mounted on the main dolly frame 74.

[0111] Operation of the Gearbox

[0112] The purpose of this main gearbox 88 is to select the dollyoperating mode by changing the ratio and/or the direction of therotational input from the front shaft 90 to a new output rotation of therear shaft 84. Two operating modes are possible in this embodiment. Wewill assume for our purposes here that the forward partial-circulartrack 100 and the rear partial-circular track 68 have the same diameterand that corresponding gears in front of the main gearbox 88 are thesame size as their corresponding gear behind the main gearbox 88. If thedirection of the input from the front is unchanged by the gearbox 88 andthe gear ratio is equal to the value calculated in the theory sectionbelow, the dolly 50 will operate in the stability mode. If the directionof the input is reversed but the gear ratio is equal to −1 (−1revolution out to the back)/(1 revolution in at the front), the dolly 50will operate in the cornering ability mode. These modes will beselectable by the driver from the cab without stopping the vehicle.Actual shifting will not begin, however, until the dolly 50 is lined upstraight forward as sensed by the rear enabling switch 150. Thisprevents the off-centering and skewing that would occur if shiftingcould be initiated at any position. In this embodiment, shifting isinitiated by activating the valve on the control box 152 in the driver'scab to place air pressure on either the stability air line 154 or thecornering air line 158. Note that a substantial interval of time mayelapse before shifting is completed, since the shifting will not beinitiated in the main gearbox 88 until the rear section of the dolly 50is in alignment as signaled by the rear enabling switch 150. Airpressure in the stability air line 154 will shift the dolly 50 into thestability mode by shifting the gearbox 88 to provide straight or forwardrotation at a gear ratio as calculated in the theory section below. Thisgear ratio will depend on the relative lengths of the dolly 50 and therear trailer 58, but will in general be around 0.75. Air pressure in thecornering air line 156 will shift the gearbox 88 to provide reversedrotation at the output with a gear ratio of −1 (−1 rotation out to theback/one rotation in from the front). Switches inside the gearbox 88will inform the driver as to which mode is currently in force byactivating indicator lights 153 on the dashboard. All mode switchactuators in gearbox 88 are stable in position so that loss of air willnot cause any mode switch In this embodiment, then, two control airlines 154, 156 and two switch indicator lines on the control box 152will comprise the communication network between the drivers cab and theswitchable geared dolly with traction kinking which is a preferredembodiment of this invention. The specifications for ordering the maingearbox 88 were given in the description section, so we will only reviewthem here. Remember that all gear shifting will be performed by highpressure air. All gear positions must be stable; i.e. no changes in gearposition can occur if no high pressure air is applied to the system. Theinput rotation enters the front of the box 88 and two gear ratios mustbe available to the shaft coming out the back. The gear shifting will beperformed by only two high pressure air lines. Pressure on the first airline, which we will call the stability air line 154, must cause theoutput rotation to be shifted to straight or forward, with the magnitudeof the gear ratio being equal to the value calculated in the theorysection for stability mode. This gear ratio will depend on the relativelengths of the dolly 50 and the rear trailer 58, but will in general bearound 0.75. Pressure on the second air line, which we will call thecornering air line 156, will cause the output rotation to be shifted toreversed with a gear ratio of −1 (−1 rotation out to the back/onerotation in from the front).

[0113] In addition to the gearing requirements, the gearbox 88 willprovide some control and information functions. The gearbox 88 mustactivate switches inside the gearbox 88 when in a particular mode whichwill show the gearbox 88 status to the driver using indicator lights 153on the control panel 152 in the drivers cab. An air valve 158 must alsobe included which is closed with its output dumped in all modes exceptcornering. This air valve 158 will be used to disable the air supply tothe traction kinking system when in the stability mode.

[0114] At this point we will also note that the two high pressure airlines 156 and 158 (FIG. 10) used to control the mode shifting must berouted from the control panel in the driver's cab to the forwardenabling switch 132 and the rear enabling switch 150. When the rearenabling switch 150 detects alignment, the air pressure is passed on tothe neutral lock gearbox 82 and the mode switching operation isinitiated. When the forward enabling switch 132 detects alignment, thisair pressure is passed on to the main gearbox 88 to allow completion ofthe mode switching operation. When the main gearbox has finished themode switching, the air pressure is passed on back to the neutral lockgearbox 86, which reconnects the back section of the geartrain.

[0115] The control box 152 will be located in the driver's cab. The faceof the control box 152 will have two indicator lights 153, one for eachmode. The control box 152 will have an air valve that will turn on highpressure air to either the stability air line 154 or the cornering airline 156, but not to both, with the other line in each case dumped toatmosphere. In review, two high pressure air lines 154, 156 FIG. 10)will be routed between the control box 152 and the dolly 50.

[0116] Operation of the Neutral Lock Gearbox

[0117] The shaft 84 coming out through the back wall of the main gearbox88 goes through another wall and into the neutral lock gearbox 86. Theneutral lock gearbox 86 performs its functions at the beginning and atthe end of each shifting sequence. When the driver has applied pressureto one of the control air lines 154, 156, and when the rear enablingswitch 150 has permitted that pressure to be transferred to the maingearbox 88, the neutral lock gearbox 86 starts a mode shifting sequenceby disconnecting all steering gears in front of the neutral lock gearbox86 from all steering gears behind it and then locking the steering gearsbehind it into a static position Then after all other shiftingoperations are completed, and when the forward enabling switch 132indicates that the forward section is aligned, the neutral lock gearbox86 completes the sequence by unlocking and reconnecting the gears behindit to the gears in front of it. Since no shifting sequence can beginunless the back enabling switch 150 has indicated that the rear sectionis in alignment and no shifting sequence can terminate unless theforward enabling switch 132 has indicated that the forward section is inalignment, this method assures that at the completion of each shiftingsequence all sections are properly aligned and centered. In practice, ofcourse, all these events may take place in a very short interval of timeif the vehicles are traveling in a straight line, since all the actionsare automatically controlled by air pressure. It is worth noting herethat while the neutral lock gearbox 86 has the back section locked, thedolly 50 will be operating in the standard non-steerable A mode. Thismode could thus be easily made available if desired, but it would havefew advantages over the other two modes that are available.

[0118] Operation of the Kinking Logic System Gearbox

[0119] The shaft 84 coming out through the back wall of the neutral lockgearbox 86 goes through another wall and into the kinking logic systemgearbox 82. The kinking logic system determines the direction and/or theamount of torque needed for proper kinking of the dolly and the backtrailer. If the tractor-trailer combination rig is making a left turn, apull to the left on the axle will indicate that the drive wheels of thedolly should be speeded up, so air pressure will be applied to the airmotors to cause the dolly to move forward faster. If the axleexperiences a pull to the right during a left turn, it indicates thatthe trailer is moving too fast, trying to push the dolly along. In thiscase, the brakes will be applied on both the dolly and on the trailer itis supporting to slow the trailer back down and prevent the dolly wheelsfrom being pushed sideways. In a similar fashion, a pull to the leftduring a right turn will cause the brakes to be applied, while a pull tothe right during a right turn will cause air to be applied to the airmotors powering the wheels.

[0120] In an air motor, an increase in air pressure causes an increasein torque. The automatic braking system is also designed so that anincrease in pressure causes more braking to be applied. The amount oftorque or braking can then be regulated by regulating the air pressuresupplied to these systems. The regulation of the air pressure isperformed by two complementary valving systems. The regulator switchesat the ends of the axle hanger assembly take in air from the main airsupply and output pressures that are related to the amount of sidewayspull experienced by the axle. These pressures are then sent to thekinking logic system, where they are further reduced if necessary, andthen sent to either the braking system or the air motors as appropriate.The screw switch in the logic system detects the angle between the dollyaxle and the centerline of the dolly. If the angle is close to 90degrees, then the dolly wheels will be nearly in line with the dolly andapplication of traction, either forward or backward, will beineffective. In this situation, the air pressure is further reduced bythe regulator switches in the kinking logic system to reduce wear andtear on the system. If the angle between the dolly axle and the dollycenterline is significantly different from 90 degrees, then the wheelsare not aligned with the dolly and traction will be quite effective inproducing kinking of the dolly. Accordingly, the regulator switches inthe kinking logic system do not reduce the pressures received from theaxle regulator switches, but simply route them to the braking system ifthe trailer needs slowing or to the air motors if the trailer needsspeeding up.

[0121] Output from the Gearbox to Steer the Dolly Axle

[0122] In FIG. 9 the shaft 80 carries the output rotational movementfrom the neutral lock gearbox 86 to the gear 78. The gear 76 then picksup this movement, ratios it back down, and converts it back to rotationabout a vertical axis. Gear 72, with the help of roller 70 then convertsthis rotational movement into movement of the rear partial-circulartrack 68 which then causes the transverse axle 64 to rotate about itscentral pivot point, steering the dolly 50.

[0123] Behavior of the Switchable Geared Dolly with Traction Kinkingwhen Backing Up

[0124] The behavior of the switchable geared dolly with traction kinkingduring backing operations is of particular interest. Normally a “double”is almost impossible to back, but if the dolly is shifted into stabilitymode, this section will behave much like a single-axle trailer with avery long wheelbase. The string will then become only slightly harder toback than a single trailer.

[0125] Summary and Miscellaneous for Switchable Geared Dolly withTraction Kinking

[0126] In summary, the input to the steering system of the dolly 50 isthe angle between the back of the forward trailer 54 and the dolly 50.The output from the system is the orientation of the transverse axle 64,and thus of the running wheels 62R and 62L of the dolly 50. Themanipulation of the input by the gearbox 88 is the key to the steeringcharacteristics of the dolly 50 in this preferred embodiment of theinvention. When the gearbox 88 is in the stability mode, the operationof the dolly 50 at higher speeds will be more stable. When the gearbox88 is in the cornering mode, the rear trailer 58 will be moremaneuverable and will have less of a tendency to cut the corners duringturning operations.

[0127] As discussed below, the length of the dolly 50 may need to beadjusted to accommodate rear trailers 58 of different lengths. This maybe accomplished by loosening the pins and locks 146 and 148, sliding theinner section of the frame 74 b into or out of the outer frame section74 a at joint 144, and then re-tightening the pins and locks 146 and148. The splined shaft 98 will slide into or out of splined shaft 90during this operation with little resistance to maintain the integrityof the steering system's rotational transfer.

[0128] A Dolly Which Uses Hydraulic Cylinders for Steering, WhichSwitches between Stability Steerable Mode and Cornering Steerable ModeUsing Air-Operated Valves, and Which Utilizes Traction Kinking forCornering

[0129] The switchable hydraulic dolly with traction kinking which ispresented in FIG. 11 is similar in many ways to the switchable geareddolly with traction kinking which is discussed above. Looking from theback of the dolly 50 forward as in FIG. 4, the two dollies would appearalmost identical. However, the switchable hydraulic dolly with tractionkinking transfers the input steering information and energy from thefront of the dolly 50 to the axle 64 of the dolly 50 via hydraulic fluidinstead of using rotary gearing. The switchable hydraulic dolly withtraction kinking also differs from the switchable geared dolly withtraction kinking in that four modes will be available instead of onlytwo. Also, the mode switching operations will be performed inside avalve box 300 rather than a gearbox 88. Each function that is performedby the gearbox 88 in the switchable geared dolly with traction kinking50 will be duplicated in the valve box 300 of the switchable hydraulicdolly with traction kinking. For simplicity, only the valves involved inswitching between stability and cornering modes and between maximum andmoderate modes will be shown in FIG. 12 and FIG. 13 respectively.

[0130] We will examine FIG. 12 first. In the two stability modes,cylinder A 348 will be connected to cylinder C 352 while cylinder B 350will be connected to cylinder D 356. The valves 302, 304, 306, and 308in FIG. 12 are shown latched into the stability mode since the airpressure is being applied to the top air cylinders 310 and 312 whichhave pushed the ganged valves to their down position. If air is appliedto the bottom air cylinders 314 and 316 instead, then the ganged valveswill be pushed to their up, or cornering, position. In this position,cylinder A 348 will be connected to cylinder D 356 and cylinder B 350will be connected to cylinder C 352. Thus, toggling this valve gangchanges the mode of the switchable hydraulic dolly between stabilitymode and maneuverability or cornering mode.

[0131]FIG. 13 shows the valves used to switch between maximum andmoderate modes. From FIG. 11 we saw that cylinders C 352 and D 356 hadidentical cylinders C′ 354 and D′ 358 located directly underneath themand attached to the same pivots. To reduce the response of the steeringsystem to a given input the hydraulic fluid from one of the frontcylinders will be shared between cylinders C 354 and C′ 356. Themovement, then, will be only half as much The same operation will beperformed with cylinders D 356 and D′ 358. In FIG. 13, air pressure fromthe upper air cylinders 320 and 322 has latched the valves 328, 330, and332 into the moderate mode, sharing the available input fluid betweencylinders C and C′ on one side and between D and D′ on the other side.This will produce only half the axle rotation for a given turn angle ofthe forward trailer that would be produced if the fluid had not beenshared. If air is applied to the bottom air cylinders 324 and 326 inFIG. 13, the valves will be latched back to their up position, themaximum mode, and the fluid will no longer be shared Now cylinders C′and D′ will share a common reservoir of fluid as their attachment pointsmove about a common pivot point at the center of the axle.

[0132] For the switchable hydraulic dolly with traction kinking, as forthe switchable geared dolly with traction kinking, mode switching willonly be allowed when the back of the dolly 50 is aligned forward. Thecontrol circuits from the drivers cab are similar except that positiveair pressure is required to toggle any of the valve gangs, requiring atotal of five control air lines. Again, switches will generate signalsto inform the driver of the dolly modes. Check valves, pressure reliefvalves, a reservoir for the fluid, and a method for maintaining someresidual pressure in the hydraulic system will be needed, but these willbe standard assemblies in standard configurations. They have little todo with the unique working characteristics of this alternativeembodiment of the invention and will not be discussed here.

[0133] The traction kinking system will be similar to the tractionkinking system for the switchable geared dolly with traction kinkingexcept that the screw shaft which keeps up with the orientation of therear section is turned by a hydraulic motor acting as a measuring devicein the hydraulic line from cylinder A. As the fluid moves into or out ofthis cylinder, the hydraulic motor will rotate this screw shaft having aregulator valve actuator block that is similar to the regulator valveactuator block 190 (FIG. 7) on the screw shaft in FIG. 7 that willcontrol regulator valves just as in FIG. 7. The kinking input system andthe kinking output system are identical to those for the gearedcornering mode dolly with traction kinking.

[0134] A Double-Axle Wagon Using Switchable Geared Type Steering andTraction Kinking

[0135]FIG. 14 shows an alternative embodiment of the invention, adouble-axle trailer or wagon 550 that utilizes switchable geared typesteering. The mechanical parts of this wagon 550 perform in much thesame manner as the switchable geared dolly with traction kinking 50except that the driver will control the mode switching operations using12 volt DC electricity from his truck battery instead of high pressureair. Enabling will be accomplished by switches instead of valves, andthe gears will be shifted by 12 volt solenoids and/or 12 volt DC motorsas required. The steerable front section of this wagon 550 will bepermanently attached to the back part of the wagon 550, so no fifthwheel connectors are needed.

[0136] The gear ratios required will depend somewhat on the wagon 550length and weight, but the same general principles that were used withthe switchable geared dolly with traction kinking 50 will apply. Whentraveling at speed, the wagon 550 will tend to be more stable usingstability type steering (a theoretical steering ratio between one andzero). This type steering will cause the wagon 550 to imitate a longerwheelbase trailer than is actually the case. For tuning corners at lowerspeeds, a negative ratio will cause the wagon 550 to swing more aroundbehind the truck, not cutting the corner, as a longer wheelbase trailerwould tend to do. The behavior of this wagon 550 during backing willalso be of interest When the stability mode is selected the wagon 550will back much like a two-wheeled trailer with a very long wheel-base.

[0137] The traction kinking system for the wagon must be modified tooperate on 12 volt DC power, and an extra battery will be needed tosupply the additional current. The air motors powering the steeringwheels will be replaced by 12 volt DC motors similar to the enginestarting motors commonly found on passenger vehicles. The regulatorswitches and valves will be replaced by variable resistance rheostats.Again, the traction kinking system will be disabled when the steeringwheels of the wagon are aligned with the centerline of the wagon tongue.

[0138] A Dolly Which Uses Microprocessors and Air Motors for Steering,Which Switches Between Stability Steerable Mode and Cornering SteerableMode Using the Software in the Microprocessors, and Which Uses TractionKinking to Assist in Turning Corners

[0139] The switchable digital dolly with traction kinking shown in FIG.15 is identical to the original switchable geared dolly with tractionkinking except that the steering information is transferred from thefront to the back of the dolly 50 by microprocessors 850 and 852utilizing compressed air as an energy source to control the steering ofthe dolly 50. All mode switching will be done by the software in themicroprocessors 850 and 852 so that no gearbox will be required. Fullredundancy has been shown for all the electronic components to minimizethe consequences of failures, although this is not necessary to theinvention.

[0140] At the front of the dolly 50, two identical optical pulserotation encoders 854 and 856 will record the rotation of the forwardgear 874 and transfer this information via pulse counting circuits 858and 860 to the two identical microprocessors 850 and 852. At the rear ofthe dolly 50 two other identical optical pulse rotation encoders 862 and864 will record the rotation of the rear gear 876. Two reversible airmotors 866 and 868 geared down to a moderate speed will provide theenergy for turning the axle 64 when the software detects that movementis required. These air motors 866 and 868 are provided with automaticbraking mechanisms which lock the gear train into position at times whenno action is required of the air motors. Loss of air pressure will alsoactivate the braking mechanisms.

[0141] The software in the microprocessors 850 and 852 will compare thenumber of rotations input from the front to the number of rotationsinput from the back. For a 1-to-1 reverse ratio, the software willcontrol the air motors 866 and 868 to force exactly the same number ofreverse rotations from the back as it received forward rotations fromthe front. A positive rotation in from the front is one that resultswhen the forward trailer turns more clockwise with respect to the dollycenterline. Other gear ratios for other modes would be handled by simplemathematical manipulation of the pulse counts from the back encoders.The primary microprocessor 850 would be in control at any time with thesecondary microprocessor 852 continually performing a check on theoperation of the primary microprocessor 850. Any significantdiscrepancies would be reported to the driver as a warning and thedriver would have the ability to switch to the secondary system if thesituation warranted it.

[0142] The alignment of the transverse axle hanger assembly is alsomonitored by the computer utilizing the input from the optical rotationencoders. Thus, the kinking logic system is also replaced in this modelby software in the computer. During a turn to the left, air pressurefrom the left regulator switch on the dolly axle is routed to the airmotors and air pressure from the right regulator switch is routed to thekinking braking system. During a turn to the right, air pressure fromthe left regulator switch on the dolly axle is routed to the kinkingbraking system and air pressure from the air pressure from the rightregulator switch is routed to the air motors. Additionally, when thedolly wheels are more in alignment with the dolly centerline, the airpressure from either regulator switch is substantially reduced to savewear-and-tear on the kinking system.

[0143] More Detailed and/or Theoretical Information

[0144] The above discussion contains all the information that isnecessary to understand the parts of the switchable geared type steeringand/or of traction kinking which are relevant to what is claimed by thispatent, but a little more detail might help the reader to understandsome of the less obvious points. The following presentation is believedto be correct, but in any case does not affect the validity or value ofa trailer system having modes that can be switched without stopping thevehicle and/or using traction kinking to assist in turning corners.

[0145] Conditions Necessary for Maximum Stability

[0146] While in the stability mode, when the forward trailer 54 tuns tothe right, the gearbox 88 causes a rotation of the dolly axle 64 about avertical axis so that the back of the dolly 50 also swings to the right,cutting across the corner as the turn is completed. If the gear ratiosare just right, the dolly 50 will stay almost exactly between the centerhitchpoint of the forward trailer and the center of the rear axle of thesecond trailer. In this configuration, the rear trailer 58 and the dolly50 act much like a single unit and handles in a manner similar to theway a single axle trailer with a very long wheelbase would handle.

[0147] In general, for the dolly 50 to remain directly aligned with thecenterline of the rear trailer 58 without sideways scrubbing of thetires the axle must be oriented according to the following formula:

tangent A=(T/L)tangent B

[0148] where:

[0149] A is the angle between the dolly axle 64 and a line perpendicularto the dolly 50 centerline,

[0150] B is the angle between the centerline of the forward trailer andthe centerline of the dolly 50,

[0151] T is the distance from the pivot point between the rear trailer58 and the dolly 50 to the center of the back axle of the rear trailer58, and

[0152] L is the total length of the dolly 50 and the rear trailer 58together, from the attachment point at the front of the dolly 50 to thecenter of the rear axle of the rear trailer 58.

[0153] If only small turning angles are considered then A isapproximately equal to tangent A, and B is approximately equal totangent B. The above formula then reduces to:

A=(T/L)*B

[0154] If the length of the rear trailer 58 is 30′ and the length of theentire vehicle assembly is 45′, the gearbox 88 must rotate the dollyaxle 2 degrees for every 3 degrees of movement between the centerline ofthe forward trailer 56 and the dolly 50 centerline. When the relativediameter of the forward 100 and the rear 68 partial-circular tracks andthe diameters of the respective forward and rear gears are known, thisrelationship will allow us to calculate the gear ratio which will berequired from our gearbox 88 to produce the maximum stability mode. Ifthe gear ratio (rotations out to the rear of the gearbox/rotations in tothe box from the front) approaches zero, the maneuverability of thelinked vehicles is improved at the expense of stability as the dolly 50approaches the configuration of the standard Type A dolly.

[0155] In the cornering mode, the switchable dolly handles as if it hadcrossed steering arms. When the forward trailer 54 turns to the right,this dolly 50 turns its steering axle to the left to swing wide aroundthe corner. The gear ratio (rotations out to the rear of thegearbox/rotations in to the front) for this mode is not as critical asfor the trailer locking stability mode. It will be clear, however, thatnegative gear ratios that approach zero will produce less pronouncedcornering capabilities but better stability as the mode again approachesthe behavior of the standard Type A dolly.

[0156] As mentioned above, steerable type B behavior is produced if welet the gear ratio of the switchable dolly approach negative infinity(infinite reversed turns out the back for one turn in at the front),that is, even the slightest turn causes a large correction and the dollyswings instantly into line behind the forward trailer. We have notedthat for this embodiment, hydraulic cylinders or some such device mustbe used to force the dolly to move in the direction perpendicular to theaxle of the dolly because the required movement is so strongly againstthe natural tendency of the system.

1. A system in an articulated vehicle that accelerates or decelerates atrailing section of the vehicle in order to produce, as needed duringcornering operations, a change in the velocity or movement of thetrailing section(s) other than the direction of the pull (or push)exerted on the trailing section by the forward section(s);
 2. The systemin claim 1 in which the change in the velocity or movement of thetrailing section(s) is achieved by applying a forward or backward torqueto the wheels of a trailing section of the vehicle, thus using theforward (or backward) traction of the wheels against the pavement toproduce the needed change in the velocity or movement of the trailingsection(s) other than the direction of the pull (or push) exerted on thetrailing section by the forward section(s);
 3. The system in claim 1 orclaim 2 in which the change in the velocity or movement of the trailingsection(s) that is needed during cornering operations causes an increase(or decrease) in the rate of change of the angle between the centerlineof the section in front of the wheels and the centerline of the sectionin back of the wheels, thus compensating for the inability of the pull(or push) exerted on the trailing section by the forward section(s) toproduce acceleration or movement as needed in a direction other than thedirection of the pull (or push) exerted on the trailing section by theforward section(s) during cornering operations;
 4. The system in claim 1or 2 or 3, in which the change in the velocity or movement of thetrailing section(s) is only caused when the vehicle is turning a corner,5. The system in claim 1 or 2 or 3 or 4 in which the articulated machineis a dolly;
 6. The system in claim 1 or 2 or 3 or 4 or 5 in which energyis added by a hydraulic motor, causing the change in the velocity ormovement of the trailing section(s);
 7. The system in claim 1 or 2 or 3or 4 or 5 in which energy is added by a combustion engine, causing thechange in the velocity or movement of the trailing section(s);
 8. Thesystem in claim 1 or 2 or 3 or 4 or 5 in which energy is added by an airmotor, causing the change in the velocity or movement of the trailingsection(s);
 9. The system in claim 1 or 2 or 3 or 4 or 5 in which energyis added by an electric motor, causing the change in the velocity ormovement of the trailing section(s);
 10. The system in claim 1 or 2 or 3or 4 or 5 in which energy is added by some other means, causing thechange in the velocity or movement of the trailing section(s);
 11. Thesystem in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 in whichthe change in the velocity or movement-of the trailing section(s) iscaused by the removal of energy by the air brakes;
 12. The system inclaim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 in which thechange in the velocity or movement of the trailing section(s) is causedby the removal of energy by the hydraulic brakes;
 13. The system inclaim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 in which thechange in the velocity or movement of the trailing section(s) is causedby the removal of energy by some other means;
 14. The system in claims 1or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 in whichthe information on the sideways force is acquired from sensors locatedon an axle;
 15. The system in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8or 9 or 10 or 11 or 12 or 13 in which the information on the sidewaysforce is acquired from a tension sensor on the tongue, a sensor thatdetermines the angle between the tongue and the wheels, and anaccelerometer mounted on the steering axle assembly;
 16. The system inclaim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13in which the information on the sideways force is acquired by some othermeans;